Okay you don't laugh at my set up here but wanted to post because it works. I used parts I got from a hardware store and a few things I had extra laying around. I figured since I like to tinker around this would be fun to do.

My smoke system works of compressed air instead of electric motors and batteries. I been wanting to add smoke to my Edge and figured I would make up something to see if it worked. I looked at the kits with motors and all and they just seemed a bit heavy to me then you still have to add the batteries. I heard a few people talking about putting a tap in the crankcase for pressure but did'nt want to do that on my new Saito.

What I did was went to K-mart and bought one of those small handheld air horns. I used that as an air tank because it was small and light. I drilled 2 holes, one for air fill which is just a air valve kind of like ones you see on bicycles. That way I could hook up a pump directly onto the tank. The other hole was a nipple that I used to run air to the oil tank. I soldered copper tubing to that nipple and ran it right into the 6 oz tank I have.

On my oil tank I have 3 lines going into it. One is the line for air, the other is the oil feed line that has the clunk on it. And the last one is vent line to allow air to bleed out as I fill the tank with oil. The oil line runs to a small needle valve I to regulate the oil flow and then into a fitting in the muffler I tapped in.

At the moment I don't have an on or off valve for the tank but intend to use one when I find one. I was looking on the ROBART website and they have what I need to make it work right. The way I control the oil flow is by pumping my air tank and then it pumps the fuel tank. I have a servo that runs a wire around the fuel line that kinks it off and on and that is what cuts my air on or off as well as my oil. I know this is not the best way but I just made this up as I went along and learning about how it works at same time. All I need is that cut off from ROBART and it should work pretty good.

Anyways I wanted to see if my set up would work on the way I have it now and see if I was going in right direction. I filled my oil tank up then cranked the engine. I am running a Saito 100 so all I needed was the oil to go into muffler and it would heat from there since supposedly 4 strokes exhaust is hotter. From what I have heard. Anyhow I cranked the engine up let it warm up then cut on my oil. It took about 5 seconds but then my smoke started. I adjusted the needle valve until I had the thickest smoke. I noticed if I turn the needle way open it wouldn't make it smoke any thicker so I have it set just as it looks like it has best flow. I was able to cut the smoke on or off and it worked good. With my small air tank I was afraid that the air would run out before the oil but it didn't. I was able to run all my oil out and still have pressure left over. I only got about 2 1/2 to 3 minutes of smoke off my 6 oz tank. I will get a larger tank to allow long smoke runs since this one works good so far. I just wanted to see if it would work at all and so far it seems like it does.

I have not flown it yet so not sure how the smoke will look in air but on ground it was pretty thick and covered up my yard. I seen where some people are making their own blend of smoke oil and thought about trying it later on. But for now I bought a jug of SUPER DRI so I would know the oil I was using would work. I didn't want to be trying to make smoke system and making up a blend at same time.

Here are some pictures on what I have now. I plan on making it much better but this is a start that hardly cost me anything. The oil was the most expensive part out of all of it. I know it looks chessy but it works!!.

FlooredCOBRA, now I have seen everything!
It looks great! Are you going to the Flying Griffins Fun FLy today?
If so, are you going to bring this beauty?

Nice innovation! I love to see ideas developed and used that can save us some $$$.

Let us know how it works out in the air.

Phil

That's brilliant! And innovative! Just the way modeling used to be... before everyone just bought what they needed over the counter or through an internet website. Well done! [sm=thumbup.gif]

Geistware , I missed out on the Griffin fun-fly. I have the flier in my car and was going to go but figured it wouldn't be much of a turn out with our nasty winds here. I ended up working on planes instead, a least got a lot done.

I haven't had a chance to try in air yet. Hoping that I will get a chance tomorrow if wind is not gusting million mph. If not I want to try out my smoke at least on ground in day time to see how it looks like. I took some pictures of it when I got it done but it was nite time. You could see smoke but only in spots. I will take some tomorrow.

Also does anyone know how many oz per minute is normal? Like what is expected out of certain tank sizes? I am trying to get an idea so I know which way to go with mine.

I found a tank full of airbrush propellant from testors and was thinking of trying your design to see if it would work. The tank Im thinking of is a 6 oz. tank fullof air but there is no PSI rating on it. How, when you fill the tank from the bike pump, do you know when it is full before the can explodes(unlikely but possible)? This is a pic of the tank I was considering.
By the way: Where did you get the valve and the nipple that you attached to the tank and how exactly did you attach them?

I got those parts from a hardware store here. They have just about anything you can think of. But one thing is those brass fittings are pretty heavy. But that is all I knew to use for my idea.

I drilled a hole in and smaller than the brass fittings. Then I just used epoxy around the threads and screwed it in place. Its hard as a rock now and don't seem like it would move. I have no clue how much pressure it can take max. Like I said I just made this up out of my head. I been pumping 30-35 lbs in that small tank. I have a gauge on my pump that I use. I found anything lower than that did not work to well.

I would like to make another tank and put the fittings used from ROBART on it. Also use high pressure lines with it. Then all I would need is one tap in my tank instead of 2. I could use some T's and then the valve and should be good to go. I also looked at the air tanks they have but there kind of big to squeeze in my plane.

I tried it out again today and found I had to much oil flowing. It was spitting out before it had time to heat up. I messed around with it to find a good middle point where it would smoke finally. For some reason I don't think the oil is heating up enough the way I have it now. It goes into muffler near the header and does work. But it is not as thick of smoke as I would like.

My engine is still new so it does idle to smooth yet. It starts to chop pop and some times backfire and reverse rotation. Today I was running my smoke when the engine slowed down and backfired. It started running backward and I never seen so much smoke come out. I mean it was really thick and looked awesome. Wish I could get it to flow like that out of the muffler. This time I was flowing out of my cowling....oops

I know it would probably be easier to go out and buy a smoke set. The way I am doing it now is aggravating but I figure it is not going to work perfect the first time I try it. It is going to take a few tries before it right if possible. I just thought it would be cool to be able to make up something cheap that would work. I like to mess around and this is giving me something to try out for fun.

I will post updates as I try different set ups on what works and does not work.

Thanks for the details of your set-up. I think it's a great idea and would love totry to put a smoke system on one of my planes. I have some time on my hands so it wont hurt to mess around a little. I let you know how mine works out when i get around to testing it. maybe within the next week.

Smoke oil flow rate should be appx 3X fuel use rate. So, using the needle for control of maximum rate... you should probably start at 3 turns.

Adjust for maximum smoke volume at 1/2 throttle and don't let any more oil flow. (you may need less than that 3 turn setting... it should be close if its a standard .40 to .60 size remote needle valve.) Maximum smoke at full throttle will rob you of too much power. you would be VERY unhappy.

Depending on your muffler setup... you can get better smoke volume by wrapping the headder pipe with a few turns of copper tube as a pre-heater. The pre-heat seems to reduce the backpressure created getting the same amount of smoke when using the stock "can" muffler that came with my O.S. .91 FS.

If you are trying to get smoke with a TUNED pipe... the setup can be simpler than yours. "T" the muffler pressure line to pressurize the smoke tank and tap into the pipe RIGHT by the header pipe for smoke oil injection. The muffler pressure point is the highest pressure place of the tuned pipe. Right at the headder is the lowest pressure point. When the smoke oil expandsion increases backpressure... it will decrease smoke oil flow (sort of a self regulation on how much it can decrease your power).

Caution... the tap-n location to inject oil into the tuned pipe can be at a VACUUM in some pipes! If yours is one of those, the valve used to shut off the oil flow has to be a good one and near the tap-in location to prevent the smoke oil continuing to dribble in.

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oops fixed

So it is okay to tap right into the header. I didn't know that.

The header on my 100 is threaded tube so may need to weld or solder my tap in header. How did you go about keeping your tap in your header? Did you use anything to make a good seal?

The header on my OS... is a relatively heavy guage (i belive stainless steel) tube Its thick enough walled that the header was easy to tap for threads. A bit of high temp Permatex (the stuff that hardens like a rock) and... the nipple is permanent.

Note... I already had a spare header pipe when I drilled and tapped one... so if it didn't work, I wasn't in trouble.

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Note also... this is NOT one of the thin wall header tubs associated with tuned pipes... DON'T try tapping into one of those.

I just got done trying out the copper tub wrapped around the header to preheat the oil. I did not yet tap my header I just wanted to see what difference the copper made compared to not using it.

When I tried it it made a huge difference in the thickness of the smoke. It was very thick starting from muffler and back. Before it was puffy and in patches and more noticeable behind the plane. Now It is very obvious it has smoke. I had a nice thick trail of smoke coming out now. The only thing is my little home made air tank sprang a leak and I would immediately loose pressure and the smoke would stop. The air tank idea did work but I need a better way to hold those fittings in the can. Also I haven't been to hobby shop yet to grab those high pressure lines. I had problems with my lines ballooning and popping off.

Cobra,

GREAT IDEA. Depending on the pressures used, should be able to get lots of flights with one fill. Pressure will control rate of flow and volume. Can't remember the formulas, but you can fit a whole room of air into a scuba tank when you pressurise it to 3000 psi. I think goldberg used to make some pinch valves made for snake valves that worked pretty good. Going to have to think about this. many of the retract system on larger scale planes used to use 2 liter pop bottles until they exploded. But at lower pressures, maybe the clear bottles would work good and be light too. Basically use a retract storage system and fill connections may work.

Mark

When you guys talk about pre-heating the smoke oil before it is shot into the muffler near the header, are you talking about wrapping the copper tubing around the outside of the muffler then soldering it to the tap near the header? I am am not quite sure what you mean by pre-heating the oil before i goes into the muffler. Thanks -ken

I am going to try again because the air pressure idea works. I just need the right parts to make it work and not come apart. It sure looked cool when all that smoke poured out the muffler.

Since I didn't have a valve for my tank it was set up direct just to see if it would work. By looking at my Gage on my air electric air pump by turnning on or off it took barely a 2 pounds to get it to smoke and with my needle valve set at 3 1/4 turns open. The needle valve I used was from a .15 size buggy engine.

avistar181 What I meant by preheating was by using the coil copper tubing and wrapping around my header. I did not solder into the muffler because this was my first time trying this out. I simply wrapped around and connected to muffler with a short piece of fuel tubing. Here is a picture I took

I just took these pictures. They are kind of blurry but can get an idea

ml3456-RCU Yeah I am going to use retract air fitting and all to try to make this work. I did notice that when I cut smoke on my rpm's would drop a little. Is this normal for it to do that?

yup

The RPM drop with smoke is why I was CAREFUL to say set for max smoke at 1/2 throttle, NOT full throttle. And don't feed ANY more oil than that.

Setting for max smoke at full throttle can mean up to 50% power loss at full throttle if the muffler has a marginal size exhaust outlet.

The expansion of the oil in the muffler will create a huge increase in backpressure. you get a loss of power from both: Increased fuel flow (muffler pressure skyrockets... pushing more fuel through the needle valve) and reduced flow in the engine (you have less of the exhaust gas leave the cylinder... and thus less fresh fuel-air mix can get in)

It would be nice to find a way to vary the exhaust outlet size with the smoke fluid flow and throttle setting (and to in-flight adjust the main fuel needle...) but that would be a monster of a setup to optimize...

Cobra,
Thanks for the pictures, they really helpme understand what you meant by preheating the smoke oil. I havent quite gotten enough time to mess wiht the idea yet but i caint wait. I figure if I keep cheking on this thread, you guys will have the set-up all tested out so i wont have to screw up an go back to fix things. You will already have done that!! J/k Thanks though for your help in describing what you have done. Its such a cool idea! Keep the updates coming
-ken

No problem, I hope to get it worked out so I can try it out in air.

FHHuber

I understand what you mean now by setting at half throttle. I am having problems with my 100 as it is with power much less loose 50% of it when smoke is on.

I seen in the latest RCM I think or maybe the Model Airplane News they had a YS in an Extra 300 they tested out. It had a Pitts style muffler bolted on it. I think a Pitts style muffler would help out a good bit since it would have 2 exits and allow for it to breath better. I am thinking not sure since I haven't tried it out. What you think about the Pitts muffler? Also I been looking all over for a Pitts for my Saito but cant find anything. What is out there that will work?

A word of advice when it comes to pre-heating... Wrap the engine cylinder, not the muffler or header. By stealing heat from the muffler, you're taking heat from the very place you need it the most.

I was looking at my engine cylinder and it looks like it would be pretty tricky. My valve stacks and the intake to carb is all in the way.

Anyone have any pictures on how they preheated the oil?

How could it really matter? If you don't preheat, you'll be putting cold oil into the muffler, it you do wrap the header to preheat, you'll be putting warm oil into cooler exhaust gasses in the muffler. If you wrap the cylinder to preheat, you'll also be cooling the exhaust gasses. I guess I can see that there may be some difference, but is it really that much, and why?

Phil

i think this is a really great idea... i will try it on my hog bipe as soon as I finish it
it will have a magnum 91 for power
any ideas on weight of the air powered system compared to the electric pump set ups?
thanks